1. Field of the Invention
The present invention relates generally to a drug delivery system, and more particularly to a labor-saving device and method for the automated delivery of medication to a patient by means of various therapies such as ultrasound therapy, sonophoresis, phonophoresis or other therapies or any combination thereof.
2. Description of the Prior Art
Transdermal drug delivery systems are well known in the prior art. There are two methods by which drugs can be delivered through the skin: passive diffusion and active diffusion. Passive diffusion involves placing a concentration of a drug in a reservoir over the surface of the skin and allowing the drug to diffuse through the skin and into the muscles, tendons, joints and bloodstream. Due to natural skin barriers, few pharmaceuticals have been successfully passively diffused into the body. With passive diffusion, if a medicine is to be effective, it must work well at relatively low dosages and be of sufficiently small molecular size that the skin will allow it to enter the body. Drugs satisfying these criteria can be applied by a therapist massaging on an ointment containing the drug with his fingertips. Examples of patented patch devices are U.S. Pat. No. 5,533,995 to Corish et al; U.S. Pat. No. 5,358,483 to Sibalis; and U.S. Pat. No. 5,356,632 to Gross et al.
A more viable way for drugs to penetrate the skin's barriers is by means of an active energy source that pushes drug molecules through the skin and, at the same time, controls the rate of delivery. An energy-driven system will allow a greater quantity of medicine and medicine of a greater molecular size to be delivered in a shorter time frame. There are two general types of active transdermal drug delivery, iontopboresis and methods using ultrasonic waves as the driving source.
Ultrasonic methods include phonophoresis and sonophoresis. Phonophoresis refers generally to the use of sound waves to enhance the delivery of topically applied drugs. Sonophoresis is similarly defined as ultrasonically induced drug delivery by using high energy ultrasonic waves to drive drug molecules through the skin. A method for applying low frequency ultrasonic waves to cause cavitation of the skin to facilitate penetration by a medicine or cosmetic is described in U.S. Pat. No. 5,618,275 to Bock. U.S. Pat. No. 5,636,632 to Bommannan et al discloses a method for enhancing the skin's permeability to a drug. In this method, the drug is delivered while applying ultrasonic waves having a frequency above 10 MHz. Other prior art transdermal drug delivery systems include U.S. Pat. No. 5,421,816 to Lipkovker and U.S. Pat. No. 5,387,189 to Gory et al.